D vs CoffeeScript
When comparing D vs CoffeeScript, the Slant community recommends D for most people. In the question“What is the best programming language to learn first?” D is ranked 28th while CoffeeScript is ranked 65th. The most important reason people chose D is:
With few exceptions, D will either compile C code to work exactly as when compiled as C, or it won't compile - it won't quietly change the semantics of C code and give unexpected results. This means that D contains an improved C, as it fails compilation where type safety is missing in C. This allows learning the same machine operations available in C and other low-level languages.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Has an improved C subset
With few exceptions, D will either compile C code to work exactly as when compiled as C, or it won't compile - it won't quietly change the semantics of C code and give unexpected results. This means that D contains an improved C, as it fails compilation where type safety is missing in C.
This allows learning the same machine operations available in C and other low-level languages.
Pro Easy to read and understand code
Pro Doesn't force you to deal with memory management
When you're just starting out, dealing with manual memory management and its bugs is a huge pain! D is garbage collected by default, which removes a huge class of things that could go wrong. And later on, if you decide you don't want or need the GC, you can turn it off.
Pro Very fast compilation
D is usually up to 10 times faster than C++. Having a language that compiles this fast means that you are free to write highly optimized code because of the relatively low cost of experimentation.
Pro Unit testing built-in
D provides unittest blocks to insert code that verifies functions preform their expected behavior and document edge cases. Since these are enabled with a compiler switch, there is no need to teach new programmers how to install new libraries and import modules, instead training on test driven design can start from the very first function.
Pro Provides a powerful data structure on top of C's arrays called slices
D provides a structure that builds on C's arrays called slices. A slice is a segment of an array that tracks the pointer and the length of the segment.
Slices are extremely powerful because they combine the protection of knowing the length of the data with the garbage collector that manages the memory backing that data, thus avoiding most memory corruption issues.
Pro It's a state-of-art evolution of C
Pro Static with type inference
For a new user adding types can feel tedious, and takes focus off the meaning of the code, but they are also important for checking logic. D provides static types, and a good system to infer types, so types are checked when calling functions, but do not need to be specified everywhere, making it feel more dynamic.
Pro Provable purity and immutability
The compiler can check that functions don't have side effects, extremely important for functional programming in concurrent scenarios, and can check immutability.
Therefore, the compiler will prove that your programs are functionally pure and respect immutable data, if you want it to.
Pro Compile-time Function Execution
Pro Built-in Unicode support
Pro Industrial quality
Pro Asynchronous I/O that doesn’t get in your way
Because all types can be treated as objects, all files can call functions in the same manner -- even stdin
and stdout
. stdout.writeln();
stdin.readln();
file.writeln();
file.readln();
Pro Easy to integrate with C and C++
D practically has the same memory structure as C and C++; all D does it build a structure around that. The entire C standard library is accessible at no cost (syntactic or speed) and it's being worked on allowing the same for the C++ standard library.
Pro Designed for concurrency and parallelism
Supports first-class functionality for both concurrency and parallelism, offered as part of the standard library.
Pro Supports calling functions from types in an object-oriented manner.
if (exists(file)) {}
may be written as if (file.exists) {}.
writeln(file);
may be written as file.writeln();
isDivisibleBy(10, 2);
may be written as 10.isDivisibleBy(2);
writeln(isEven(add(5, 5)));
may be written as 5.add(5).isEven().writeln();
Pro Compiles to readable Javascript
With CoffeeScript, there's never really a question of what is going on. If you're worried that something went wrong in the compilation process, the output is very human readable and mostly 1 to 1 with the CoffeeScript code, making debugging easier as the code that is being executed by the interpreter can be double checked.
Pro Widely used
CoffeeScript is the most popular of the compile to Javascript languages, so long term support is much less of a worry than with others.
It also means there are many plugins and tools for integrating it into many different build systems, giving it it nearly universal support.
Pro Lightweight syntax
Javascript is a very verbose language so CoffeeScript's goal is to lighten it to make it less tedious.
Various design choices are built around making CoffeeScript more terse with things like optional parenthesis in function calls, cleaner function declarations, no curly braces, and significant white space. Because Javascript can get pretty deeply nested at times, having a lightweight syntax helps with readability.
The result is a language with a minimalistic syntax with lots of syntax sugar.
Pro It's just JavaScript
The golden rule of CoffeeScript is: "It's just JavaScript". The code compiles one-to-one into the equivalent JS, and there is no interpretation at runtime. You can use any existing JavaScript library seamlessly from CoffeeScript (and vice-versa). The compiled output is readable and pretty-printed, passes through JavaScript Lint without warnings, will work in every JavaScript runtime, and tends to run as fast or faster than the equivalent handwritten JavaScript.
Pro Syntax for humans, not compilers.
CoffeeScript adds syntax that is not only more terse than javascript, smoothing over the rough edges, but also enforces a more human readable syntax to the point where a non-programmer can understand some logic.
Many programmers that are not use to coffeescripts syntax will find it foreign if they don't read the single page API, but generally it is quick to understand and although self documenting code is a myth coffeescript is definitely very close.
if hungry then eat food for food in fridge when food isnt poison and it isnt bedtime
Seems a lot more concise and comprehensible to many programmers and most others than the alternative syntax:
var food, i, len;
if (hungry) {
for (i = 0, len = fridge.length; i < len; i++) {
food = fridge[i];
if (food !== poison && it !== bedtime) {
eat(food);
}
}
}
Pro Function syntax is great for callbacks
Passing functions as callbacks is central to how Javascript is written, but the default syntax for functions is very verbose and hard to read. Various CoffeeScript syntax decisions help with ease of writing and reading functions.
The most obvious change is that the function keyword is changed from function
to ->
. Writing out the word function
is very clunky especially when you need to use multiple nested functions.
One of the more opinionated choices of CoffeeScript is the use of significant whitespace, and optional parens around function arguments. While this can be used poorly, it can also be used to great effect with nested functions. For example, a function that takes an object that defines anonymous functions will end in a mess of parens and curly braces:
asyncAction({
success: function(data){ /* handle data */ },
error: function(error){ /* handle errors */ }
});
In CoffeeScript you could rewrite this as:
asyncAction
success: (data) -> /* handle data */
fail: (error) -> /* handle errors */
Other helpful features are automatic returning of the last statement to make short anonymous functions easier so (a, b) -> a+b
would replace function (a, b) { return a+b; }
, as well as binding functions to the current context object with =>
.
Pro Splats
Because Javascript functions can take variable amounts of parameters, it is helpful to be able to use splats to extract an array of arguments in a function.
For example, if you have a function like: (a, b, rest...) ->
any amount of parameters sent to the function after a
, b
will be stored in an array in the variable rest
. You can also put splats at the start or middle of the arguments list, such as (a, middle..., b) ->
.
When calling a function you can use a splat to apply an array as arguments as well.
Pro Everything is an expression
Even for
loops and if
statements. For example, to get mapped array, you don't have to use any Array methods, just the language features:food = ( stuff for stuff in fridge when stuff.isEatable() )
Pro Familiar to Ruby programmers
CoffeeScript was created by a Ruby programmer and a number of syntax features are modelled on Ruby equivalents, so will be familiar to Ruby programmers. For example, implicit returns, i.e. the last variable of each function is implicitly returned, so "return" keyword need not be present.
Pro Extremely easy to document with literate coffeescript
Skip the documentation build, just write documentation with literate CoffeeScript.
CoffeeScript has a literate mode which let's you use markdown (used by almost everything, such as reddit, github, stack exchange, etc) with code indented how you would normally in markdown and simply enables you to run the code.
This enables you to quickly write FORMATTED, custom documentation that's easily displayed with no build step for the documentation.
Pro Source maps allow you to debug code in CoffeeScript
With source maps, you can get the proper location of where an error occurred directly in precompiled code, making it easier to debug without the tedious step of translating the compiled code back to the original code in your head.
Pro Significant whitespace
Having indention-based code blocks is particularly helpful in JavaScript because of its functional callback based nature. In JavaScript you find yourself writing functions within object and passing functions to functions. You can find statements ending with a confusing melange of braces like )}})})
. With significant whitespace, most of the needs for braces go away.
Pro Default choice for Ruby on Rails
Pro Maintainable code
Easy to read and easy to work with structures like list.
Cons
Con Poor adoption even after many years of existence
There's a widely accepted perception of D as a language that has been poorly adopted. Since adoption is driven by perception this becomes a fact. So managers and engineers start becoming nervous in adopting a language that has such a perception among the community and that has been so unsuccessful for so long.
Con Failed at becoming alternative to C or C++
Almost as confused and complicated as C++, but without the popularity and widespread corporate usage. Also failed at becoming a good cross-platform GUI application development language like Object Pascal. Many missed past opportunities, and now newer languages are better alternatives.
Con Lack of vision
D is community-driven and lacks the support of any large corporation. While this increases the amount of talent and engineering abilities of the people working on D, it also brings a severe lack of charisma, leadership and vision.
Con Garbage Collection
Memory is not managed directly.
Con All the downsides of garbage collection without any of its benefits
When D decided to implement garbage collection it instantly alienated a large community of developers (C and C++ programmers). For them, the official policy has been: "Don't want garbage collection? Use D with RAII or manual management style!".
While true, it's also absolutely pointless because there's little to none support for alternate memory management styles in the standard library, which means that a new user will have to start with a language that is stripped down of the core infrastructure.
On the other hand, for those people who want to use garbage collection, the implementation of it is lackluster.
Con Terse syntax can lead to ambiguity
It can sometimes be hard to be sure of what CoffeeScript will compile down to because of the optional parentheses and significant white spacing. Over multiple lines the same statement can be written in many different ways, and it's not always clear what the intended interpretation is.
For example:foo bar and hello world
can compile to either:
foo(bar) && hello(world)
foo(bar && hello(world))
Con Initializing a variable and assigning it are essentially the same thing
Because of how variables are initialized and reassigned in CoffeeScript, it becomes very easy to accidentally overwrite a variable as the codebase increases. As complexity increases, the only way to safely create a variable is by pressing Ctrl + F and by examining the current file to ensure that there's no conflict.
Con Last expression is returned by default
While this is a pro for small functions, it requires self-discipline to check if unnecessary overheads are introduced:
eat_full = ->
for food in fridge
break if full
cook food if food.requires_cooking()
eat food
This will return array of eat
function results. Can be fixed by adding empty return
at the end.